Development of a simple liquid chromatographic method with UV and mass spectrometric detection for the separation of substances related to amoxicillin sodium

The development of a selective method for the separation and identification of amoxicillin sodium-related substances is described. It is based on reversed-phase liquid chromatography followed either by UV detection (LC-W) or by mass spectrometry (LC-MS). Mass detection was carried out by an atmospheric pressure ionization source and ionspray interface. Flow injection analyses-MS gave positive-ion mass spectra exhibiting abundant peaks due to their protonated molecules without significant fragmentation. The protonated molecules were used for selected ion monitoring LC-MS analyses. The method allowed the resolution of 13 available potential impurities from amoxicillin and from each other. Its applicability to an MS detector also permits a rapid identification of the impurities in the lack of the corresponding reference substances. (C) 1998 Elsevier Science B.V.